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I just purchased a forclosure and discovered the upstairs A/C tripps the circuit breaker immediately when turned on. I thought it might be the run capacitor, but the guy at the store tested it and said it was ok. I'm hoping it's not the compressor, but it is looking that way. Is it still possible that the capacitor is bad? Any suggestions would be helpful. By the way I opened the circuit outside before the condensing unit and the breaker did stay in.

It maybe a loose connection. If it's not that you would be well advised to call a pro and have the system checked out completly. They may find other problems with your system that can save you money in the future.

I have seen some wacky stuff at older foreclosed cribs, it seems that when people get down on their luck and broke some real creative solutions to household problems can be done!!!!!!!you would probably come out way ahead to get a tech to look at this unit and any other at your new place. I worked on a unit several years ago that had a partial 12 ounce can of R134a stored in the closet with the evap and a line tap on the line, just a coincidence I am sure. Good Luck

Take care

"but the guy at the store tested it and said it was ok."

How did the guy test it?
Was it the Run Capacitor?
Or the Start Capacitor?
Or is it a Combo Start/Run?
How many microfarads capacitance is a rated?
How many percentage points was the existing within the rating?

Does the system have an auxiliary "hard start" capacitor and relay in the compressor circuit?

Bad Capacitors? The EZ ones look bulged out on top... But then again many others fail with no visible exterior indication.

Best test? Swap it out for a known good of the same size, that way you're certain and at worse out twenty bucks... Sound like a plan?

If you do not know exactly what you're are doing it may prove to be the last task of your lifetime... Capacitor store a significant charge and you had better know all about discharging them safely or you are decidedly in serious harms way...

This isn't a joke; please call a professional immediately if you’re not highly competent in the service of this type of component.

BTW: Any time you’re working inside the unit, always have one hand in your pocket, that way at least when it hits you your heart’s rhythm may possibly survive the event, otherwise you’ll have maybe six minutes a best to get to a defibrillator unit to correct the ventricular tachycardia or fibrillation.

Re: Take care

Originally posted by faith "but the guy at the store tested it and said it was ok."

How did the guy test it?
Was it the Run Capacitor?
Or the Start Capacitor?
Or is it a Combo Start/Run?
How many microfarads capacitance is a rated?
How many percentage points was the existing within the rating?

Does the system have an auxiliary "hard start" capacitor and relay in the compressor circuit?

Bad Capacitors? The EZ ones look bulged out on top... But then again many others fail with no visible exterior indication.

Best test? Swap it out for a known good of the same size, that way you're certain and at worse out twenty bucks... Sound like a plan?

If you do not know exactly what you're are doing it may prove to be the last task of your lifetime... Capacitor store a significant charge and you had better know all about discharging them safely or you are decidedly in serious harms way...

This isn't a joke; please call a professional immediately if you’re not highly competent in the service of this type of component.

BTW: Any time you’re working inside the unit, always have one hand in your pocket, that way at least when it hits you your heart’s rhythm may possibly survive the event, otherwise you’ll have maybe six minutes a best to get to a defibrillator unit to correct the ventricular tachycardia or fibrillation.

Take care...

HAHAHA,

If the breaker keeps tripping, then you have either a bad breaker, a bad compressor or possibly a bad factory start capacitor or maybe a wire is grounded to metal or the compressor wires fell off terminal block. A run cap would not make the breaker trip, call a hvac tech out , as no matter what the problem they would have the expierence to fix it, don`t you have a home warranty?

I appreciate the the help, but I think a little more info on my part would help. The breaker pops instantly when the A/C is turned on. I first pulled the breaker outside(on side of house) to isolate the short and confirm the problem was on the outside unit. I pulled the power wires off the compressor and the breaker stayed in when I turned the A/C on again. I rung out the compressor terminals to the compressor casing to see if there was a short to ground and it checked out good. I wanted to make sure the run capacitor was ok, so I took it to the store. I hope he checked it out right. The run capacitor is a dual run cap for the fan and the compressor. The rating is 3/30 microfarad. He said it read right. But from what I've read. It could still be bad. I also pushed the main contactor in with the compressor disconnected and the fan powered normal. Is it possible that the run capacitor can still cause the breaker to trip? Maybe the breaker is bad.